The British South Africa Company (BSAC) was a mercantile company incorporated on 29 October 1889 by a royal charter given by Lord Salisbury, the British prime minister, to Cecil Rhodes. The company was modeled on the East India Company and was expected to annex and then administer territory in south-central Africa, to act as a police force, and develop settlements for European settlers. The charter was initially granted for 25 years, and was extended for another 10 in 1915.
It was intended that the BSAC would develop the region without significant cost to the British tax payer. It was therefore given the right to create its own political administration supported by a paramilitary force for protection of settlers against local peoples.
Profits form the company, in terms of diamond and gold interests were reinvested in the company to allow it to expand its area of influence. African labor was exploited partially through the application of hut taxes, which required Africans to look for wages.
Mashonaland was invaded by a Pioneer Column in 1830, then the Ndebele in Matabeleland. This formed the proto-colony of Southern Rhodesia (now Zimbabwe). They were stopped from spreading further to the north west by King Leopolds holdings in Katanga. Instead they appropriated lands which formed Northern Rhodesia (now Zambia). (There were failed attempts to also incorporate Botswana and Mozambique.)
The BSAC was involved in the Jamison Raid of December 1895, and they faced a rebellion by the Ndebele in 1896 which required the aid of British to quell. A further rising of Ngoni people in Northern Rhodesia was suppressed in 1897-98.
Mineral resources failed to be as large as implied to settlers, and farming was encouraged. The charter was renewed in 1914 on the condition that settlers be given greater political rights in the colony. Towards the end of the last extension of the charter, the company looked towards South Africa, which was interested in incorporating Southern Rhodesia into the Union. A referendum of the settlers voted for self-government instead. When the charter came to an end in 1923, white settlers were allowed to take control of the local government -- as a self-governing colony in Southern Rhodesia and as a protectorate in Northern Rhodesia. The British Colonial Office stepped in 1924 and took over.
The company continued on after its charter lapsed, but was unable to generate sufficient profits for shareholders. Mineral rights in Southern Rhodesia were sold to the colony's government in 1933. Mineral rights in Northern Rhodesia were retained until 1964 when they were forced to hand them over to the government of Zambia.